1. Field of the Invention
The present invention relates to a power source control device of a car telephone mobile station system.
2. Prior Art
FIG. 1 is a block diagram showing a car telephone mobile station system in the prior art. In FIG. 1, numeral 1 designates a body device, numeral 2 designates a hand set, numeral 3 designates a connector which connects the body device 1 to the hand set 2, and numeral 4 designates a battery which supplies power to the car telephone mobile station system. Also numeral 5 designates a body control unit (hereinafter referred to as "body CPU") which performs control within the body device 1, numeral 6 designates a radio transmitting/receiving circuit which performs radio transmitting and receiving to an exchange under control of the body CPU 5, and numeral 7 designates a power source circuit which performs ON/OFF control of the power supply from the battery 4 to the body device 1 and through the connector 3 to each circuit in the hand set 2, and the body 1 is provided with these various circuits. Further, numeral 8 designates a hand set control unit (hereinafter referred to as "hand set CPU") which transmits or receives signals to or from the body control unit 5 and performs control within the hand set 2, numeral 9 designates a momentary switch as a power source switch which transmits power source control signals for the ON/OFF control of the power source circuit 7, numeral 10 designates a voice circuit which transmits or receives voice signals to or from the radio transmitting/receiving circuit 6 of the body device 1 by talking, and numeral 11 designates a key input circuit connected to the hand set CPU 8, and the hand set 2 is provided with these various circuits. Also numeral 12 designates a power source input terminal for the power source circuit 7, numeral 13 designates a power source output terminal therefor, and numeral 14 designates an input terminal to which power source control signals from the momentary switch 9 of the hand set 2 are inputted.
Next, operation of the system will be described. When the hand set 2 is normally connected through the connector 3 to the body device 1, if the momentary switch 9 is operated, a power source control signal by grounding is produced, and transmitted through the connector 3 to the body device 1 and then inputted to the input terminal 14 of the power source circuit 7. The power source circuit 7 in the OFF-state is turned on by inputting the power source control signal to the input terminal 14, and this state is held. Since the power source circuit 7 is turned on, the power supply inputted from the battery 4 to the power source input terminal 12 of the power source circuit 7 is supplied from the power source output terminal 13 to the body CPU 5 and the radio transmitting/receiving circuit 6 within the body device 1, and further through the connector 3 to the hand set CPU 8, the voice circuit 10 and the like within the hand set 2.
Since the car telephone mobile station system in the prior art is constituted as above described, if the power source circuit 7 remains in the ON-state and the hand set 2 is disconnected from the body device 1 by the connector 3, the power source circuit 7 is held to the ON-state, thereby the power source continues to supply power to the body device 1 and a problem is produced from the viewpoint of safety. Further if the hand set CPU 8 runs away, the user must operate the momentary switch 9 so as to turn off the power source circuit 7 once, and operate the momentary switch 9 again so as to turn on the power source circuit 7, and reset the hand set CPU 8 thus another problem is produced.